I would second the proposition that you should look into taking a Hunters' Ed. course, especially if you plan to eventually trying your hand at turning Bambi into little white packages. (As an aside, the disassembly of critters is a good more work than it shows on the u- tube videos.)
As regards the idea of 'starting out' with a cap lock, I am of two minds: one side says that cap locks are simpler and this would be a good idea, but then again, you're going to drop a pretty good chunk of change on something that you don't really want: you want a flinter, right? So buy a good (not necessarily expensive) one and then figure out how to make go bang on a reliable basis . I.E. a Thompson Center (i started with one of these) or a Lyman, or, if you have the money, a Kibler. The Kibler (either Southern Mountain Rifle or their Colonial Rifle) is a first rate kit, and will last you and your heirs a lifetime if properly maintained ... check out the website, but leave your credit card in another room. If you can hook up with a club, see if someone can show you the intricacies of loading and firing a flint lock rifle. I was not able to do this when i started out, and the learning curve was a good bit longer and steeper for me. And the 'net didn't exist (i'm an old guy) so there was only the guy at the gun store to tell me what i was doing wrong. Luckily, i managed to figure it out without blowing myself or someone else into small bits.
Some books you should buy:
the Dutch Schoultz method (link already mentioned) ... is pointed mostly at cap shooters, but the method will work for flint shooters, too ... best non- shooting accessory that you can buy, to my mind.
if you decide to build your own, you will need some tools but first some books. Get the books now, because there's a wait if you buy from Kibler. (If you get any of the other "kits," you should be warned that these are bot 'tab "A" into slot "B" propositions, and will take a good nit more work that it appears at first glance. You can buy rifles "in the white," but they will have to be finished (i.e. stock sanded, stained and finished, metal parts blued or browned, etc) before you would want to bring it into the field... same with any "kit" don't think 'kit,' but rather a set of parts.
If you buy tools, avoid 'sets' of things: you will spend a boatload of money on a set of chisels and only use two or three ...
The Gunsmith of Grenville County, Alexander ... here's a link:
https://www.trackofthewolf.com/Categories/PartDetail.aspx/303/1/BOOK-GGCa bit spendy, but an excellent treatise on how to build them. (as in, if you go the Kibler route you
need/want this at your bench) ... great for explaining why you do the steps in the order that you do them. spiral bound so it stays flat ... obviously designed by someone who uses it - a very good thing.
Recreating the American Longrifle, Buchele,
et al. here's the link
https://www.trackofthewolf.com/Categories/PartDetail.aspx/303/1/BOOK-RALagain, a bit extravagant, but another excellent book on how the parts fit together
sorry to run long ...
don't hesitate to p.m. me if you have specific questions, and
Make Good Smoke!